Effect of Milling Time Parameter on the Microstructure and the Thermoelectric Properties of n-Type BI2TE2.7SE0.3 Alloys

PROPERTIES OF N-TYPE Bi 2 Te 2.7 Se 0.3 ALLOYS Nanostructured thermoelectric materials receiving great attention for its high thermoelectric performance.In this research, nanostructured n-type Bi 2 Te 2.7 Se 0.3 alloys have prepared using high energy ball milling and followed by spark plasma sintering.Also, we have varied ball milling time to investigate milling time parameter on the thermoelectric properties of n-type Bi 2 Te 2.7 Se 0.3 powder.The powders were discrete at 10 min milling and later particles tend to agglomerate at higher milling time due to cold welding.The bulk fracture surface display multi-scale grains where small grains intersperse in between large grains.The maximum Seebeck coefficient value was obtained at 20-min milling time due to their lower carrier density.The κ values were decreased with increasing milling time due to the decreasing trend observed in their κ L values.The highest ZT of 0.7 at 350 K was observed for 30-min milling time which was ascribed to its lower thermal conductivity.The Vickers hardness values also greatly improved due to their fine microstructure.